There are no real rules about Greek salad, but there are key ingredients. My version has the following:
1 beefsteak tomato, or the equivalent in small tomatoes, coarsely chopped
red onion, a bit more than a quarter of a whole onion, somewhat finely chopped
about six Kalamata olives, chopped
half a small cucumber, chopped into large dice
Bulgarian, Israeli, or ‘sweet’ feta cheese, in chunks (set on top rather than mixed in, as this will break the cheese up too much)
finely snipped fresh basil leaves, about one to 1½ tablespoons
salt, pepper, and generous drizzle of cold-pressed olive oil
Note: If you really want lettuce as well, lettuce doesn’t spoil a Greek salad. Add your leaves and consider it more interesting!
The salad, just before the last-minute sprinkling of the sea salt and drizzling of the olive oil. Note, however, the abundance of fresh-ground black pepper!